An ordinary air pot can discharge water simply by pressing. However, its pressure conduit, water conduit and water outlet are open and in daily application, the water is not insulated from the environment so that water temperature can not be maintained for a long time. Once hot water is poured in, the water becomes warm after a certain period because of cooling. Furthermore, when water is to be discharged from an air pot, it is not possible to find the temperature and volume of the water therein till pressure is applied and the water is discharged. Hence it may be found that the water is insufficient or the temperature is not high enough for preparing a cup of hot coffee, or milk. There are thus a plurality of inconveniences in application, which are defects of an ordinary air pot.